Pipe coupling for a pneumatic follow-up system



Aug. 2, 1960 P. F. K. ERBGUTH 2,947,553

PIPE COUPLING FOR A PNEUMATIC FOLLOW-UP SYSTEM Filed Nov. 7, 1955 2 Sheets-Sheet 1 ia l 4 a2 65 :3 SUPPLY AND 70 I RECEIVING mass 22 PAUL E K. E'RBGUTH IN VEN TOR.

OR/VEY 1960 P. F. K. ERBGUTH 2,947,553

PIPE COUPLING FOR A PNEUMATIC FOLLOW-UP SYSTEM Filed Nov. 7, 1955 2 Sheets-Sheet .2

67 nlH ,lu mu H mil n PAUL F. K. ERBGUTH INVENTOR.

TOR/V5 Y Paul F. K. Erbguth; GieahNeclr, bi.Y.,.assigno'r,' mesne assignments, to. Daystrom, .1n corporated, Murray Hill, N.J., a corporation of New Jersey Filed Net. '7; russgser. $215,109 i can. (ci. its-133") This. invention relates topneumatic' systems and, more particularly, to such comprising a vane carried by a r'otatable pointer and movable between a nozzle fromwhicli low pressure air fio'ws and .a" coaxially-dispo'sed nozzle receiving air from the first-mentioned nozzle, except when cntiolf by the vane, improved means being provided for maintaining said nozzles in alignment; the system also ineluding an improved form of coupling rotatable coaxially with the pointer and on which the nozzles are mounted, with relay means to cause. the rotatable'coupling to follow, the movement of said pointer.

. Pneumatic systems of the class contemplated by this invention comprise a device or mechanism for sensing changes in a variable condition, examples being electrical measuring instruments with pointers indicating current or voltage, and devices with parts like pointers movable .in response to changes in. weight,- humidity; etc. Such de'-. vices may be associated with pneumatic relays or couples comprising a discharge nozzle from which an elastic fluid flows under low pressure .and a cooperatingreceiving nozzle aligned with the discharge nozzle to receive elastic fluid therefrom, except as cut 01f by a vane carried by the sensing mechanism... l l The present application is directed to an improved form of nozzle support, in which misalignment of the nozzles is prevented by having them formed in a rigid U-shaped block so that a stream of air is directed from la: nozzle openingat the inner surface of one arm o'fsaid block toward a gooperatingjnozzle opening at the inner surface of the other arm o f said block. Th PIe'se'nt application also covers. an improved form of coupling, or air; bea in s n o t 991v miwudn h t nsuppo t between spaced bearings as has been the practice hereto fore;

An object of this invention is the provision of a pneumatic system in whicha vane isnormally disposed in an, air stream flowing betweemtwo nozzlesforrned. in a rigid U-shaped member, and including a coupling rotatableco} axially withthe vane carrying means and supportedat only one end; said coupling also having air tubes issuing therefrom and communicating ,with .the nozzles, and means effective upon movement of theyane' to correspondingly rotate the coupling, thereby to maintain the vane in a throttling positio1r in the air stream.

An obiectofthis inventionis to provide an improved form ofair bearing for a pneumatic system using a rotatav51y msn fidn nq z e co p y 1 is of, t s .i vs t n i t p i an air bearing for-a P sm t s s em om is n su p i g bracket with 5i} supply and receiving connections, a pair of concentrically-disposed tubes ,sealed againsteach other at both ends, the outer tube haying a pair of radially-opening holes and being partly threaded, and abarrel carrying nozzle tubes and a nozzle couple screwed onto the threaded portion of said outertube, whereby air can flow from the supply connection of the bracket. through. the

mneitube to the barrel, from there throughonenozzle tube to its nozzle and, if not intercepted, to the other W P ies 0 2,947,553 Patented A 2, 969

nozzle, throughits. nozzletubebackto thea barrel, .and from there. .throughthe,outerorlhreaded. tube to the receiving connection of the supporting bracket. An object of this..invention. .is..to providearotatably mounted. nozzle. couple. .in. whichmisalignment of ..the nozzles is preventedby forming ,eachinan .arm ofa rigid U-shaped member adapted tobecarried by nozzle tubes. These and other objects and advantages of the .invem tion willobec'ome apparcntfrorn the, following description when taken withthe accompanying drawings. ..It will. be understood, however, that the. drawingsarefor purposes of illustration and are no.t;.t0..be construed. as defining the scope .or spirit of the invention, reference being had for the latter purpose .to the. claims; appended hereto... ,In ,the, drawings, wherein. like. reference characters denote like parts .in the. several views: T Figure 1,.is. a. diagrammatic representation of .an .electro-pneumatic follow-up system embodying my. invention; Figure 2 is. aperspective vicwofapreferred form of rotatable coupling carryingyalig'ned. nozzles; i .Figure 3 is ,an axial sectional view on the. line .III.-III of Figure 2,.in .the directionof the arrows, with the plane of the. supply and receiving tubesflrotated about the axis of the coupling, so that for clarity both of said tubes appearin elevatio'na Figur"e .4 is an ,axial sectional View of the coupling bar rel. Of ur fi parated. from the associated parts; .Figurej isjan 'axialsectional .view, of the air bearing tube assernbly of Figure 3, separated from the associated P Ll, g .Figurefi is a, vertical sectional view. on the line .V.I VI of,Figure 2, in Ihe direction of the arrows, showing the details of the nozzle assembly; and Figure ;7 is a fragmentary plan andpartlyehorizo'ntal sectional view on the planefiofthe line VII'VII of Figure 1,.in the direction of the arrows.

R'eferenceis now made to Figure 1, which illustrates an electro-pneurnatic follow-up system in which is pro-. posed to.be incorporated the improved airbea'ring and I QZZIc assembly of my invention. Here the conditionsensing device is an electrical instrument, such as a milli voltmeter, having a vane .21 secured to its pointer. 22. The instrument may be of conventional construction, having a wire wound movable coil 24 rotatable on pivots 25; 26 between the poles N of a permanent magnet (not shown). Each of the pivots has secured thereto a hair spring 27; .28 which hold.the coil in a given zero position until an electric current flows therethrou'gh. Such current may be generated by a thermocouple 29 serving as a terriperature-sensing element in a furnace ("not shown). The instrument may include a scale 30 calibrated in suitable values as, for example, temperature. .o flhe vane 21 is movable upon rotation of the pointer 22 between apairof axially aligned spaced nozzles 31, 32; Thesenozzles form a pneumatic. couple and are carried by a hollow coupling .33 mounted for coaxial rotation with respect to the pointer, as by the pivots 34, 35. A spring 36 11a's one end fastenedto the. pivot 35 and the other end to a fixed member 38, said spring being arranged to bias the coupling 33 in a counter-clockwise direction, that is, to return it toward the left or zero position of the pointer relative to the scale 30. A wire 65 is tightened around the coupling and has one end secured thereto and the other end to an arm or crank 64 on a hand hollow interior cavity thereof, by means of a tube 42. From the interior cavity at the right hand, air passes through tube 44 to an air relay 45. The structural details of the coupling will be described hereinbelow with reference to Figures 2 to 5, inclusive, and the structural details of the nozzle couple will be described with reference to Figures 2 and 6.

The air relay 45 comprises a chamber closed by a diaphragm 46 connected to a lever 47 that is pivoted to the relay housing as indicated at 48. At its other end, the lever carries a flapper 49, normally disposed adjacent to nozzle 51 from which air flows. The nozzle 51 is supplied with air under pressure, through a tube 52, which contains a flow restrictor 53. In general, the air pressure within the tube 52 is of the order of pounds per square inch. On the other hand, the pressure of the air in the tube 43 is very low, in the range of less than 3 inches of water, thereby eliminating adverse reaction between the vane and the air stream flowing between the discharge nozzle 32 and the receiving nozzle 31. When the pressure in the tube 44 decreases, due to the vane passing further into the air stream between the nozzles 32 and '31, from an assumed balanced condition in which the leading or up-scale (that is, to the right as viewed in Figure 1), edge of the vane 21 is disposed substantially in the center of the air stream, the diaphragm 46 moves downwardly, moving the flapper 49 closer to the nozzle 51, and correspondingly effecting an increase in pressure in the tube 52 and the bellows assembly 54, connected thereto by the tube 55. It will be understood that in practice one edge of the vane 21 normally is disposed in the air stream and it is the movement of this vane in the air stream which inhibits more or less the flow of air from the discharge nozzle to the receiving nozzle.

Upon an increase in air pressure in tube 52, the bellows 54 is'cornpressed. A rod 57 has its lower end secured to the bottom'of the bellows and its upper end pivotally-connected, as at 58, to a crank 56 that is secured to the shaft 59. Consequently, a compression of the bellows results in a counter-clockwise rotation of the shaft 59 and a clockwise rotation of the coupling 33 by means of the crank or arm 64 and the operating wire 65 against the action of the biasing spring 36. It will be apparent, then, that an upscale movement of the pointer,

resulting in a movement of the vane further into the air stream, results'in a corresponding rotation of the coupling 33 until the vane again occupies substantially its initial, or throttling, position in the air stream. In order to prevent movement of the vane 21 beyond the air stream upon upscale deflection of the pointer a suitable stop 55 is secured to the nozzle 32. The shaft 59 may also operate an arm 63 carrying a pen cooperating with a movable chart (not shown) to form a recorder. Obviously, such record will correspond to the position of the instrument pointer, or the instantaneous state of the variable condition under consideration.

A down-scale movement of the pointer 22, or one to the left as viewed in Figure 1, results in the vane 21 being moved further out of the air stream, increasing the air flow into the receiving nozzle 31, whereupon the air pressure in the tubes 42, 44, and in the air relay chamber 45 is increased. This results in a reverse operation, whereby the diaphragm 46 moves upwardly, moving the flapper 49 farther from the nozzle 51, and correspondingly effecting a decrease in pressure in the tubes 52, 55, and the connected bellows assembly 54. This causes the bellows assembly 54 to expand, resulting in a clockwise rotation of the shaft 59 and a counter-clockwise rotation of the coupling 33 by the return or biasing spring 36.

Referring now to Figures 2 to '5, inclusive, for preferred details of the rotatable coupling 33 and the parts asso-' ciated therewith, it will be seen that this coupling, here designated 33a, is in the form of a cylindrical member, or barrel 70 shown in detail in Figure 4, having a hollow cavity 66. This barrel portion also has two radial holes 4 '67, 68 and is partly threaded, as indicated at 69 and 71. Preferably, a fine thread, such as 100 threads per inch, isused. The barrel 70 carries the nozzle tubes, here designated 43a, 42a communicating respectively with the apertures 68 and 67, as shown most clearly in Figure 4.

Threaded into the barrel is an outer tube or shaft 72 carrying coaxially therewith an inner tube or hollow shaft 73. The outer tube 72 carries threads 74 and 75 respectively, fitting the threads 69 and 71 of the barrel. The inner tube 73 is open at its ends, and the outer tube 72 is closed around the circumferential space between the ends of the tubes but has radial openings 76 and 77. The opening 76 communicates with the chamber 78 formed between the barrel 70 and the exterior surface of the tube 72 and from which the aperture 67 extends. The inner tube 73 communicates with end chamber 79 in the barrel 70, from which the aperture 68 extends.

The other end of the tube 72 is non-rotatively supported in a bore 81 in a column or pillar 82, secured to a base or bracket 83 by means of screws 84, as shown in Figure 2. The aperture 77 in the outer tube 72 communicates with an aperture 85 in the column '82 from which extends receiving tube 44a, corresponding with the tube 44, of Figure 1. Air is supplied to the end cavity 86 in the column 82 through aperture 87 therein, by means of supply tube 39a corresponding with the tube 39 of Figure 1.

As shown in Figure ,2, the biasing hair spring 3611 is, in the present embodiment, secured to the barrel 70, its outer end being anchored to the base or bracket 83 in any de sired manner as by means of an overlying clip (not shown). From this description it will be seen that the coupling 33a is supported by only one end of the outer 1 tube 72. Undesired axial movement is prevented by the threaded engagement between said outer tube and the barrel 70, the coacting threads being very fine.

It will be understood that during operation the flow of air through the nozzle tubes 42a, 43a, shown in Figure 2, is identical with the flow of air through the nozzle tubes 42, 43 of the Figure 1 arrangement, the improvements residing in the structural details of the rotatable member which requires only a single bearing and in the construction of the nozzles per se.

The construction of the nozzles is shown in Figure 6. Here there is shown a U-shaped block 88, of suitable material. A small diameter hole is drilled through the arms of the block to form the discharge nozzle 32a and the receiving nozzle 31a. An enlarged diameter bore is then drilled part way through each arm, the bore in the lower arm accommodating the nozzle tube 43a and the bore in the upper arm being closed by a plug 89. A lateral bore 91 is also formed in the upper arm, such bore communicating with the said first bore formed in such arm and accommodating the nozzle tube 420:. Such arrangement results in the precise alignment of the discharge and receiving nozzles 32a and 3111, respectively.

Referring back to Figure 3, it will now be clear that the flow of air through the rotatable couple is as follows: supply tube 39a, aperture 87, inner tube 73, chamber 79, aperture 68 and nozzle tube 43a which connects directly to the discharge nozzle 32a shown in Figure 6. The return flow of air is through the receiving nozzle 31a and nozzle tube 42a (Figure 6), then through the aperture 67 (Figure 3) chamber 78, radial hole 76 in the outer tube 72, the space between the outer and inner tubes, radial aperture 77, aperture and tube 44a. The latter tube 44a corresponds to the tube 44 shown in Figure 1. In a low pressure air system the fine threads of the tube 72 and the barrel 70 results in very little escape of air between these two parts. A completely sealed system may be provided by applying a light coating of a suitable grease on these cooperating threads.

From the foregoing disclosure it will be seen that I have provided a pneumatic follow-up system responsive to changes in a variable condition as, for example, temsensing device of electrical character.

perature. The system is self-balancing and any displacement of the vane 21 results in a corresponding follow-up rotation of the aligned nozzles to thereby return the system to its initial balancing, or throttling point, since the position of the rotatable coupling carrying the aligned nozzles will always correspond to the position of the instrument pointer. The actual deflection of the instrument can be recorded by a pen actuated by the arm 63 of Figure 1, movable in accordance with the rotation of the rebalancing shaft 59. Also, since the air pressure effective to move the bellows assembly 54, varies in accordance with the position of the instrument pointer, suitable remotely-positioned indicating and/ or control apparatus can be actuated by connecting the same to the tube 55.

While I have described a specific pneumatic system including an improved form of coupling and nozzle assembly, it will be apparent that my pneumatic follow-up arrangement is not restricted for use with a condition- Any movable pointer or lever system may be utilized to move the vane in the air stream. 1

Having now described my invention in detail in accordance with the requirements of the patent statutes, those skilled in this art will have no difiiculty in making changes and modifications in the individual parts or their relative assembly in order to meet specific requirements or conditions. Such changes and modifications may be made without departing from the scope and spirit of the invention, as set forth in the following claims.

I claim:

11. A rotatable coupling member for a pneumatic system comprising a first supporting member with a bore, a pair of coaxially-disposed tubes telescoped with respect to and sealed against each other at both ends, one end portion of the outer of said tubes being non-rotatably supported in said bore and the other end portion thereof having external threads, a barrel with a cavity internally threaded and fitted on said external threads, a pair of nozzle tubes extending radially from said barrel and axially spaced therealong, an enlargement in said cavity intermediate the ends of said threads, one of said nozzle tubes communicating with said enlargement and the other nozzle tube communicating with the end portion of said cavity beyond the ends of said coaxially-disposed tubes, an air supply connection with the bore of said supporting member beyond the supported end of said coaxiallydisposed tubes, and an air receiving connection with said bore short of said supported end, an aperture in said outer tube communicating with said receiving connection and another aperture in said outer tube communicating with said enlargement, whereby air can flow from the supply connection of the supporting member through the inner tube to the barrel, from there through one nozzle tube and through the other nozzle tube back to the barrel, and from there through the outer tube to the receiving connection of the supporting member.

2. A rotatable coupling member; for a pneumatic follow-up system having a vane movable by a member in response to changes in a variable condition, a pair of axially-aligned nozzles disposed on opposite sides of the vane and carried by a member supported at only one end, means normally maintaining an air stream between the nozzles, air-operated means responsive to changes in the air pressure Within one of the nozzles as brought about by movement of the vane in the air stream, and mechanism responsive to the said air-operated means to rotate the member in correspondence with the movement of the vane; comprising a rotatable coupling member including a fixed supporting member with a bore, a pair of coaxially-disposed tubes telescoped with respect to and sealed against each other at both ends, one end portion of the outer of said tubes being non-rotatably supported in said bore and the other end portion thereof having external threads, a barrel with a cavity internally threaded and fitted on said external threads, a pair of nozzle tubes extending radially from said barrel and axially spaced therealong, an enlargement in said cavity intermediate the ends of said threads, one of said nozzle tubes communicating with said enlargement and the other nozzle tube communicating with the end portion of said cavity beyond the ends of said coaxially-disposed tubes, an air supply connection with the bore of said supporting member beyond the supported end of said coaxially-disposed tubes, and an air receiving connection with said bore short of said supported end, an aperture in said outer tube communicating with said receiving connection and another aperture in said outer tube communicating with said enlargement, whereby air can flow from the supply connection of the supporting member through the inner tube to the barrel, from there through one nozzle tube and through the other nozzle tube back to the barrel, and from there through the outer tube to the receiving connection of the supporting member.

References Cited in the file of this patent UNITED STATES PATENTS 28,648 Campbell June 12, 1860 1,479,656 Fetterley Jan. 1, 1924 1,851,723 Neidow Mar. 29, 1932 1,991,432 Valentine Feb. 19, 1935 2,058,642 Sperry Oct. 27, 1936 2,228,022 Ziebolz Jan. 7, 1941 2,254,098 Ziebolz Aug. 26, 1941 2,362,581 Newcomb Nov. 14, 1944 2,418,653 McCormack Apr. 8, 1947 2,568,092 Sloan Sept. 18, 1951 2,710,598 Bass June 14, 1955 2,775,254 Stanbury Dec. 25, 1956 2,791,451 Roston May 7, 1957 2,794,444 Markey June 4, 1957 FOREIGN PATENTS 390,550 Germany Feb. 20, 1924 458,823 Great Britain Dec. 28, 1936 493,452 Great Britain Oct. 7, 1938 831,161 Germany July 8, 1949 933,896 Germany Sept. 8, 1955 

